In free convection the two dimensionless numbers are grashof's number & prandtl number where it is replaced by reynold's number & prandtl number for forced convection.

Sanju said:
(Nov 11, 2013)

In free convection h is function of Pr number and Gr number.

In forced convection h is function of Pr number and Re number.

Sudheer said:
(Jun 23, 2015)

In free convection the two dimensionless numbers are Grashof's number & Prandtl numberwhere it is replaced by Reynold's number & Prandtl number for forced convection. In free convection h is function of Pr number and Gr number.

Prandtl number, Grashoff's number. In forced convection h is function of Pr number and Re number.

Sai Krishna said:
(Jul 15, 2015)

Would you please explain me Reynold's number, Grashof's number and Prandtl number?

Rohit said:
(Oct 1, 2015)

Reynolds number = Re = Inertia forces/Viscous forces.

Re = VD/v or (rho*V*D)/mu.

Prandtl number = hl/k.

Grashoff's number = (rho*g*B*l2*dt3)/mu.

Ayyappa said:
(Oct 27, 2015)

In free convection Reynold's number matters. It is simply function of Grashoff's and prandtl.

Amulraj said:
(Apr 2, 2016)

Refer heat and mass transfer data book CP Kothandraman. It contains all the formulas and relations.

Gaurav said:
(Dec 16, 2017)

Critical value in free convection is Grashoff number only.
Nusselt number is a function of GR No and PR No.
So the answer should be B.

Sreerag said:
(Dec 24, 2017)

@Rohit.

I think Prandtl no = meu. Cp/k.

Jonty said:
(Aug 6, 2018)

In free convection Nusselt number is a function of Re and Gr, on the other hand it is a function of Re and Pr for forced convection. So, answer C is correct.